THE ROOT DISTRIBUTION OF PLUM TREES TRAINED TO FOUR DIFFERENT SYSTEMS
The majority of the roots were in the upper 40 cm of soil. Root length density in the surface soil varied from 0.8 cm cm-3 for the Lincoln canopy to almost 1.4 cm cm-3 for the vase canopy. Averaged over the whole profile, root length density between the rows decreased from 0.5 cm cm-3 50 cm from the trunk to half this amount 3 m away. An exception was the vase system which had 1.8 cm cm-3 at 50 cm from the trunk. This may be because the trees were larger than those in the other systems. The vase system had the highest root density in the top 45 cm of soil. Root number density in the region down to 60 cm depth was highest for the tatura trees. This may be because they were planted at higher density than in the other training systems. Root number and root length density decreased exponentially with depth. We need to establish whether these differences are important in water use by the canopies.